if ... then语句
if [ test_command ]then
commands
fi
if ... then ... else语句
if [ test_command ]then
commands
else
commands
fi
if ... then ... elif ... (else)语句
if [ test_command ]then
commands
elif [ test_command ]then
commands
......else
(optional)commands
fi
for ... in语句
for 变量 in
变量列表do
commands
done
while语句
while 条件为真do
commands
done
until语句
until 条件为真do
commands
done
case语句
case $variable inmatch_1)
commands_to_execute_for_1;;
match_2)
commands_to_execute_for_2;;
match_3)
commands_to_execute_for_3;;
......*)
(可选 - any other value)commands_to_execute_for_no_match
;;
esac